Orders for Up To 1,700 Hybrid Buses Will More Than Double Existing GM-Allison Fleet
22 January 2008
Allison Transmission has received major orders from transit agencies in Washington, D.C., Philadelphia and Minneapolis/St. Paul for up to 1,732 GM-Allison hybrid-powered buses (earlier post). The hybrid technology is licensed by General Motors to Allison Transmission, which assembles and sells the hybrid transmission to bus manufacturers.
These new deliveries will more than double the current fleet of nearly 1,000 GM-Allison hybrid buses, and potentially include the largest single hybrid bus fleet acquisition yet—an order for 952 by the Washington, D.C. Metropolitan Area Transit Authority.
In addition, the Southeastern Pennsylvania Transportation Authority’s order for 480 hybrid buses, as well as Minneapolis/St. Paul Metro Transit’s plan to purchase up to 300 hybrid buses, will bring the number of GM-Allison hybrid buses to more than 2,700 units in 81 cities in the US, Canada and Europe. The GM-Allison hybrid system to-date has operated successfully for more than 55 million in-service miles without an end-of-life battery failure.
By the end of 2008, GM will offer eight hybrid models using either GM’s two-mode hybrid system or the more affordable GM Hybrid Belt Alternator Starter system. Through 2011, GM intends to introduce 16 hybrid models, an average of one every three months.
GM debuted the hybrid technology for transit buses in 2003.
According to a study conducted in 2006 by the National Renewable Energy Laboratory (earlier post), transit buses with GM-Allison’s hybrid technology delivered 26.8% better fuel economy in in-use evaluation, and up to 75% better fuel economy on the Manhattan test cycle than traditional transit buses. Emissions of nitrogen oxides (NOx) are reduced up to 39%, particulate matter (PM) up to 97%, carbon monoxide up to 60% and hydrocarbons up to 75%, depending upon the test cycle.
| GM-Allison Hybrid vs. Conventional Bus NREL Test Results | |||||
|---|---|---|---|---|---|
| Manhattan | OCTA | CBD | KCM | In-Use Atlantic Base | |
| Fuel economy (mpg, % increase) | 74.6% | 50.6% | 48.3% | 30.3% | 26.8% |
| Fuel consumption (gram/mi, % reduction) | 42.9% | 33.7% | 32.8% | 23.4% | 21.2% |
| NOx (gpm, % reduction) | 38.7% | 28.6% | 26.6% | 17.8% | – |
| PM (gpm, % reduction) | 92.6% | 50.8% | 97.1% | ns | – |
| CO (gpm, % reduction) | ns | 32.0% | 48.0% | 59.5% | – |
| THC (gpm, % reduction) | ns | ns | 75.2% | 56.3% | – |
Resources
King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results (NREL/TP-540-40585)
Why is there that disparity in fuel consumption, one time measured in mpg, the other one in g/mi (who the hack came up with that mix-up? When will the US public finally learn, that even there the SI units shall be used since more than 100 years ago)
Provided the two engines (HV / non-HV) use the same type of fuel, the same percentage would be expected...
Odd... Or is this another artefact of the odd way of measuring consumption in the US? (as compared to the rest of the world, where SI units are used)...
Posted by: realarms | 22 January 2008 at 12:11 PM
Yes, the units may be confusing, but the math works out the same regardless of what units you use.
For example, take the 74.6% increase in mpg. So that's 1.746 times the normal mpg. Do 1 / 1.746=.573 So that's 0.573 times the fuel used from before. So 1-.573= 42.7% reduction.
So really, the two numbers are redundant (and a little confusing). I wish everyone would just go to CO2 g/km. That would eliminate the US/British gallon confusion and correct for the higher density of diesel and also allow for other fuels to be measured in a semi-comparable way.
Posted by: Karkus | 22 January 2008 at 12:23 PM
@ realarms
The cause of the disparity appears to be a simple algebra problem. Let's say the average hybrid bus gets 6.34 mpg and the non-hybrid 5.00 mpg. The % mpg INCREASE is (6.34/5.00-1)x100=26.8%. For fuel consumption REDUCTION, (1-5.00/6.34)x100=21.1%.
However I agree that using SI units most of the rest of the world would be exceedingly rational.
Posted by: maxpower | 22 January 2008 at 12:40 PM
Even people using SI units can miss a trick, like the Japanese who use km/litre. It's still a measure of "mileage" when the "efficiency" is a more relevant presentation of the information.
CO2 g/km is what I remember in my head these days when comparing things, and better than fuel efficiency, but still not optimal. For example it will allow H2 cars to brag about 0 g/km when they have just caused CO2 output elsewhere in the system. Lets quote kWh/km and split the car properties from the fuel properties (well to car CO2/kWh for example).
And going beyond the pale, I'd like to swap from kWh to Joules.
Posted by: DavidJ | 22 January 2008 at 01:48 PM
On topic, I wonder if either the Allison or the Orion is "better", or if it just depends upon duty cycle
Posted by: DavidJ | 22 January 2008 at 01:53 PM
Hybrid buses make sense in terms of lower pollution and running costs. Hopefully hybrid buses and other heavy vehicles with stop-start running like garbage trucks and city delivery vehicles will soon become standard, at least as a transition to full EV's.
I don't know of any hybrid buses running here in Australia yet. Maybe the purchase price premium is still scaring off potential buyers or they are just hard to get.
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Posted by: Rafael Seidl | 23 January 2008 at 09:30 AM
The GM hybrid bus is very impressive compared to the typical old fashioned diesels, but I doubt the optimistic fuel savings stated are backed up with actual data from real world operation. As this 2004 article in the Seattle PI says...
"Hybrid buses' fuel economy promises don't materialize"
http://seattlepi.nwsource.com/transportation/203509_metro13.html
Posted by: gary | 23 January 2008 at 09:32 AM
Gary, way to go! You are spot on with your choice to completely ignore all of the details laid out in the report.
Hybrid buses used on "Express" routes? Yeah, I have ridden those buses from the Federal Way transit center to downtown Seattle. Nearly 90% highway travel with 3 or 4 highway side stops made along the 20 mile route.
Posted by: Patrick | 23 January 2008 at 09:44 AM